QUANTITY OF BLOOD. 103 



the water from the parenchyma of the organs permeated with 

 capillary vessels, the excess thus obtained is so completely 

 counteracted by the deficiency caused by the retention of 

 some blood in the capillaries, and in part by transudation, 

 that our estimate of the quantity of blood contained in the 

 human body may be considered as slightly below the actual 

 quantity." 1 



In extreme obesity, the weight of the blood would not 

 bear a natural ratio to that of the body ; but from the data 

 which we have at our command, we may state the proportion 

 in a well-formed man to be about 1 to 8, or the whole quantity 

 of blood at from 16 to 20 pounds avoirdupois. The quantity 

 of blood undoubtedly varies in the same individual in differ- 

 ent conditions of the system ; and these variations are fully 

 as important, in a physiological point of view, as the entire 

 quantity. 



Prolonged abstinence has a notable effect in diminishing 

 the mass of blood, as indicated by the small quantity which 

 can be removed from the body, under these circumstances, 

 with impunity. It has been experimentally demonstrated 1 

 that the entire quantity of blood is considerably increased 

 during digestion. Bernard drew from a rabbit weighing about 

 2 Ibs., during digestion, over 10J ounces of blood without 

 producing death ; while he found that the removal of half 

 that quantity from an animal of the same size, fasting, was 

 followed by death. In Burdach, 3 we find a case reported by 

 Wiisberg, of a female criminal, very plethoric, from whom 

 21 Ibs. Yf ounces of blood flowed after decapitation. As the 

 relations of the quantity of blood to the digestive function 

 are so important, it is unfortunate that in the observations 

 of Lehinann and Weber, the conditions of the system in this 



1 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. L, p. 638. The 

 weights of the body and the entire quantity of blood have been reduced from 

 grammes to pounds avoirdupois. 



2 BERNARD, Liquides de V Organisme, tome i., p. 419. 

 9 Op. cit., tome vi., p. 119. 



